#include<iostream>
#include<cmath>

using namespace std;

int main()
{
    double n, l, r, x;
    cin >> n;
    l = 0,x = r = fabs(n);
    while(r - l > 1e-8)
    {
       double mid = (l + r) / 2;
       if(mid * mid * mid >= x) r = mid;
       else l = mid;
    }

    if(n >= 0 ) printf("%.6lf\n", r);
    else printf("-%.6lf\n", r);
    
    return 0;
}